title: A new dinuclear Ru-Hbpp based water oxidation catalyst with a trans-disposition of the Ru-OH.
abstract: The bis(2-pyridyl)ethylamine (bpea) ligand has been used as a starting material for the synthesis of dinuclear Ru complexes of general formula trans,fac-{[Ru(n)X(bpea)](2)(μ-bpp)}(m+) (for X = Cl, n = II, m = 1, trans-Ru(II)-Cl, 1(+); for X = OH, n = III, m = 3, trans-Ru(III)-OH, 2(3+)) where the 3,5-bis(2-pyridyl)pyrazolate anionic ligand (bpp) acts as bridging dinucleating ligand, the bpea ligand coordinates in a facial manner and the monodentate ligands X are situated in a trans fashion with regard to one another. These complexes have been characterized in solution by 1D and 2D NMR spectroscopy, UV-vis and electrochemical techniques and in the solid state by X-ray diffraction analysis. The reaction of 1(PF(6)) with Ag(+) generates the corresponding solvated complex where the Cl ligand has been removed as insoluble AgCl, followed by the oxidation of Ru(II) to Ru(III) to generate the corresponding dinuclear complex trans-Ru(III)-OH, 2(PF(6))(3). The latter has been shown to catalytically oxidize water to molecular dioxygen using Ce(IV) as oxidant. Quantitative gas evolution as a function of time has been monitored on line by both manometry and mass spectroscopy (MS) techniques. Relative initial velocities of oxygen formation together with structural considerations rule out an intramolecular O-O bond formation pathway.
authors.affiliation: Departament de Química and Serveis Tècnics de Recerca (STR), Universitat de Girona, Campus de Montilivi, E-17071, Girona, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Mola
authors.forename: Chiara
authors.initials: C
authors.lastname: Dinoi
authors.forename: Xavier
authors.initials: X
authors.lastname: Sala
authors.forename: Montserrat
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Isabel
authors.initials: I
authors.lastname: Romero
authors.forename: Teodor
authors.initials: T
authors.lastname: Parella
authors.forename: Xavier
authors.initials: X
authors.lastname: Fontrodona
authors.forename: Antoni
authors.initials: A
authors.lastname: Llobet